Van drives into bay off Marina Green

Vehicle hits water off the Marina Green

A diver holds up a crowbar while searching for the van that drove into the water off the Marina Green in San Francisco.

Photo By Ian C. Bates/The Chronicle

People watch as rescue boats from the San Francisco Police department and United States Coast Guard search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

San Francisco Police and United States Coast Guard rescue boats search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

People watch as rescue boats from the San Francisco Police department and United States Coast Guard search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

Firefighters watch as rescue boats from the San Francisco Police department and United States Coast Guard search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

Prakash Sootarging uses binoculars to watch as rescue boats search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

People watch as rescue boats from the San Francisco Police department and United States Coast Guard search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

Pedestrians watch as San Francisco Police officials and the United States Coast Guard search for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

Divers talk with officials from the San Francisco Police Department and the United States Coast Guard while searching for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

Photo By Ian C. Bates/The Chronicle

A diver searches for a car that drove into the water near Marina Green in San Francisco, Calif. on June 21, 2013.

A person was found dead Friday night inside a van that drove into the bay off the Marina Green in San Francisco, authorities said.

The victim's gender and name were not immediately released. The San Francisco medical examiner will conduct an autopsy to determine the cause of death.

Witnesses reported seeing the van careening through a nearby parking lot at about 20 mph just after 5:05 p.m., said Assistant Fire Chief Bob Postel. The van jumped a curb near the San Francisco Marina Yacht Harbor and flew into the bay.

The van quickly sank into the water, which is estimated to be 20 to 25 feet deep. About 8 p.m., divers were able to find the van using sonar equipment, and the lone occupant was found dead inside, said Officer Gordon Shyy, a San Francisco police spokesman.

Earlier, rescuers pulled three people from the bay after they jumped in to help the person trapped in the van. John Pollak, 13, of San Francisco, saw the three people dive off a boat and swim to the vehicle, which was still visible minutes after it went into the bay.

"They were just banging on the windows, trying to break the windows in," he said. "They started banging on the back door. They were just trying to get someone out."

John, who was playing catch with his father when the van went into the bay, said the person looked unresponsive and was possibly unconscious. He could not see if the person was a man or a woman.

Firefighters described the dark water as having next to zero visibility.